Fact: if you have n readers check you work for typos, the n+1 reader will find a previously undiscovered typo with 42/n seconds of looking at the work.
Fact: If you open your book and successfully fix a typo, you will introduce (6.5x-y)/3 new typos, where x is the number of keystrokes used to fix the typo and y is the number of pages in the chapter.
Further research is needed to verify the constants across multiple writers. This may all just be me.